(1) Field of the Invention
The present invention relates to a catalyst material for use in producing an SNG (Substitute Natural Gas) and a method for producing the SNG, and more particularly to a catalyst material and a method for producing the SNG efficiently at a low temperature from a source gas containing a reducing gas and at least one of carbon dioxide and carbon monoxide. It is possible to produce an SNG gas in a more efficient and simpler manner than when a conventional catalyst is used and not only from carbon monoxide but also from carbon dioxide.
(2) Description of the Related Art
An example of a method for synthesizing SNG from a source gas containing at least one of carbon dioxide and carbon monoxide, and reducing gas such as hydrogen is disclosed in Japanese Patent Application Kokai Publication No. Hei 6-248275. This publication discloses an apparatus for producing a substitute natural gas for use as a city gas in which the main component is methane formed from vapor reformation using fossil hydrocarbon as a source gas and, in which a PSA (Pressure Swing Adsorption) step for separating hydrogen gas by treating the gas produced in a carbon monoxide reformation step is added, and a methanation step for converting to methane a gas produced at a low temperature reformation step and a gas produced from the PSA step is provided.
However, in the method disclosed in Japanese Patent Application Kokai Publication No. Hei 6-248275, it is necessary to supply for the hydrogen gas for the methanation using the PSA step separately, so that the number of steps is increased. In the method disclosed therein, the hydrogen is separately supplied because the activation for methanation of carbon monoxide by methanation catalyst (Ni catalyst) is small. In the Ni based catalyst conventionally used as a catalyst for the production of SNG, the degree of methanation of the carbon dioxide is smaller than that of the carbon monoxide so that, when the carbon monoxide and carbon dioxide co-exist, only the carbon monoxide is methanated unless it is conducted under a temperature above 400.degree. C., which means that practically no methanation occurs in the carbon dioxide. Even if the methanation does occur in the carbon dioxide, the rate of the methanation is extremely small as compared with that in the carbon monoxide.